140G-J3F3-D20

The 140G-J3F3-D20 circuit breaker is a J Frame circuit breaker from Allen-Bradley/Rockwell Automation. It employs a fixed thermal/adjustable magnetic trip type. Also, the 140G-J3F3-D20 circuit breaker has a molded case. Note that it is possible to use molded case circuit breakers to provide branch protection for motor loads. However, the NEC states that a device that is providing motor branch short-circuit protection and ground fault protection should be able to carry the entire starting current of the motor. The 140G-J3F3-D20 circuit breaker, as with other short-circuit protection devices, can be used to provide protection in a panel where only motor loads are being fed by the breaker, or in a panel where fixed loads are being fed by the breaker, or in a panel where mixed loads are being protected by the feeder breaker.

The Allen-Bradley 140G-J3F3-D20 circuit breaker, like other 140G molded case circuit breakers, is rated for operation at a maximum altitude of 6560 feet. Note that the breaker’s voltage rating drops with an increase in altitude. For example, at 9840 feet, the voltage rating stands at 90%, while at 13,120 feet and at 16,400 feet, the voltage rating stands at 79% and 67%, respectively. Additionally, the breaker’s current rating derates with an increase in altitude. For instance, at 9840 feet, the 140G-J3F3-D20 circuit breaker has a current rating of 98%, and at 13,120 feet, it has a current rating of 93%. Also at 16,400 feet, the circuit breaker has a current rating of 90%. Note that the breaker has a 100% voltage and current rating at an altitude of 6560 feet.